
Andy C. answered 07/20/18
Tutor
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Math/Physics Tutor
n(n-4) = 60
n^2 - 4n - 60 = 0
( n - 10 )(n + 6 ) = 0
n-10 = 0 ---> n = 10 ---> 10*(10-4) = 10*6 = 60
n+6 = 0 --> n = -6 ---> -6 * (-6-4) = -6 * -10 = 60